For instance, one such generally-known integral power steering device has been disclosed in Patent document 1.
That is, this type of integral power steering device is mainly comprised of a housing main body constructed by a substantially cylindrical bottomed gear housing and a valve housing that closes the opening of the gear housing, a power cylinder configured to partition the internal space of the gear housing into two pressure chambers by a piston linked to a steering shaft for generating a steering assist torque, and a rotary valve disposed in the valve housing and configured to selectively supply appropriate hydraulic pressure required for generating the above-mentioned steering assist torque to each of the pressure chambers of the power cylinder depending on the steering direction and steering torque. A pair of valves, namely a first valve and a second valve, each serving as a stroke limiter for restricting a stroke position of the piston, are provided so as to face the respective pressure chambers, namely the first pressure chamber and the second pressure chamber.
The first valve and the second valve are configured such that their valve bodies are accommodated and disposed in respective valve accommodation holes formed in the housings, and that their valve elements are slidably fitted on the inner peripheral side of each of the valve bodies. When the hydraulic pressure in each of the pressure chambers reaches a pressure level greater than or equal to a predetermined value, pin members, which are linked to the respective valve elements, are pushed or forced toy means of the piston, and thus the valves are opened. Hence, fluid-communication between the pressure chambers is established, and as a result an excessive rise in hydraulic pressure in each of the pressure chambers can be suppressed.